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secondo/Algebras/Pregel/Operators/OnMaster/StartPregel.cpp
2026-01-23 17:03:45 +08:00

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C++

/*
----
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Copyright (C) 2004, University in Hagen, Department of Computer Science,
Database Systems for New Applications.
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----
//paragraph [1] Title: [{\Large \bf \begin {center}] [\end {center}}]
//[TOC] [\tableofcontents]
[1] Header File of the class of operator ~setPregelFunction~
November 2018, J. Mende
[TOC]
1 Overview
This header file contains definitions of type mapping, vallue mapping and the operator specification.
2 Defines and includes
*/
#include <StandardTypes.h>
#include <regex>
#include "StartPregel.h"
#include "../../Helpers/Commander.h"
namespace pregel {
ListExpr StartPregel::typeMapping(ListExpr args) {
if (!nl->HasLength(args, 1)) {
return listutils::typeError("You must provide 1 argument.");
}
const ListExpr rounds = nl->First(args);
if (!CcInt::checkType(rounds)) {
return listutils::typeError(
"The first argument must be of type int");
}
return nl->SymbolAtom(CcBool::BasicType());
}
int StartPregel::valueMapping(Word *args, Word &result, int, Word &,
Supplier s) {
result = qp->ResultStorage(s);
CcInt *rounds = (CcInt *) args[0].addr;
PRECONDITION(PregelContext::get().isReady(),
"Please run \"query setPregelFunction(...) first.\"")
if (!rounds->IsDefined()) {
BOOST_LOG_TRIVIAL(error) << "rounds is undefined";
((CcBool *) result.addr)->Set(true, false);
return -1;
}
auto connections = PregelContext::get().getConnections();
auto query = "query startPregelWorker(" +
std::to_string(rounds->GetValue()) + ");";
supplier<Runner> runners = [&connections, &query]() -> Runner * {
WorkerConnection *connection;
if ((connection = connections()) != nullptr) {
return new Runner(connection, query);
}
return nullptr;
};
auto queryResponses = Commander::broadcast(runners, Commander::isTrue, true);
bool allSuccessful = true;
bool *response;
while ((response = queryResponses()) != nullptr) {
if (*response == false) {
allSuccessful = false;
}
delete response;
}
((CcBool *) result.addr)->Set(true, allSuccessful);
return 0;
}
OperatorSpec StartPregel::operatorSpec(
"int -> bool",
"# (_)",
"This operator starts the Pregel computation on the distributed workers."
"You must provide a maximum number of supersteps that should be executed."
"The operator always returns TRUE.",
"query startPregel(10);",
"This operator belongs to the Pregel API."
"It may require knowledge of the system to effectively understand and "
"use all the operators that are provided."
);
Operator StartPregel::startPregel(
"startPregel",
StartPregel::operatorSpec.getStr(),
StartPregel::valueMapping,
Operator::SimpleSelect,
StartPregel::typeMapping
);
}